What are some likely ethical issues arising from such testing? If people are using marijuana for medical reasons, they will most likely test positive for the drug's presence all the time, yet they will need to be able to drive. How can a "legal limit" be reasonably set if intoxication is not measured by certain tests?

Drug  testing allows the right to privacy for medical users.

Explanation:

Marijuana is also called weed herb and has addictive properties. Being psychoactive drug marijuana has highly addictive qualities and is overdose is believed to intoxication. Due to the drug increased intoxication can lead to dependence and hence create various problems thus testing is need. The controller substance act under the federal law has legalized the use of substances for adults in accordance with the state law. The drug can is allowed for medical reasons and this includes a background check.

Water flows along the east coast and across the western tropical pacific towards south america, while they both are directed towards that way,  el niño does not directly affect the southern flow of water along the coast. 

D. latin america followed by africa